The objective of the proposed research is to develop a multichannel implantable stimulator for selective activation of different diameter fibers of peripheral and central nerves. The most immediate application of the selective activation technique is restoration of micturition and defecation in individuals with spinal cord injuries. Although funding has been awarded to develop the electrode delivery system for this application, there are no commercially available implantable stimulators that can be used with the system as the technique is based on manipulating the nonlinear properties of voltage gated ion channels using pulse waveforms that currently available implantable stimulators cannot produce. In addition to the specific waveforms, experiments show that effective selectivity in the sacral roots requires six isolated output channels. In order to test the feasibility of the overall project, Phase I will develop a circuit design that can meet these requirements and will evaluate the design on a breadboard. If successful, Phase II will construct the design in a circuit assembly using Multi-Chip Module technology, develop a RF power and communication link between the stimulator and an external controller, develop the implantable package, and conduct thorough testing of the overall system. PROPOSED COMMERCIAL APPLICATION The control of the bladder and bowel have a major financial impact on the well being of paraplegics and quadriplegics. These patients often require costly health care for treatment of complications in these systems. It is estimated that there are 176,000 people in the United States alone with paralysis due to spinal cord injury and at least 8000 new injuries occur each year.